Sacoglossan sea slugs make routine use of photosynthesis by a variety of species‐specific adaptations

Abstract

Abstract The phenomenon of the uptake, intracellular sequestration, and subsequent usage of algal chloroplasts by the digestive cells of many species of sacoglossan sea slugs, currently called kleptoplasty, has been of considerable interest since its discovery in the 1960s. While a large body of literature reported that captured chloroplasts were photosynthetically active inside slug cells and that plastid longevity in some species might be the result of the horizontal transfer of functional algal nuclear genes into the slug genome, a few recent studies have called the older results into question. Here, we have reviewed the literature and showed that while kleptoplasty occurs in many slug species and almost all derive benefit from kleptoplast photosynthesis, the slug adaptations to maintain the chloroplasts differ from species to species. These adaptations range from behavioral to molecular, including gene transfer, in a variety of combinations.